a) Technical Field of the Invention
The present invention relates to an improved structure of a driving mechanism for venetian blinds, and in particular, a driving mechanism employing a reinforcement section mounted at the two lateral walls of a fixing seat, and in combination with a lateral wall cord-fixing hole and a blocking section, and a positioning section on a slat control element to ensure that slat control element is positioned at the two lateral walls of the fixing seat.
b) Description of the Prior Art
There are numerous types of driving mechanism for Venetian blinds available in the market. For example, as shown in FIGS. 6 and 7, a driving mechanism having a frame body 10 is provided with two groups of fixing seat 20, and the center of the top section of the two lateral wall 21 is pivotally mounted with a blind slat control element 30 driven by a control shaft 40. A pulling cord 50 is mounted at the top of the blind slat control element 30 and is used to pull up main cords 51 located at the two sides of the pulling cord 50. The two main cords 51 respectively pass through the pulling cord hole 220 at the bottom section of the fixing seat 20, and in combination with the suspension cord 60, via the suspension cord hole 221 located at the bottom section 22 of the fixing seat 20 to control the up and down movement and angle of variation of the blind slats 70. A clipping cord 52 is provided in between the two main cords 51 for the mounting of the blind slats 70.
A hole 71 is provided to the blind slat 70 to allow the passage of the suspension cord 60. The bottom of the blind slat 70 is provided with a base blind 80 to combine with the suspension cord 60 and the end of the pulling cord 50 as a unit. However, this structure has the following drawbacks:
(a) As the blind slat control slats 70 and the fixing seat 20 often cause friction, and the control shaft 40 is made from metal material while the fixing seat 20 made of plastic material, the rotating of the control shaft 40 being provided with polygonal control shaft 40 will damage the positioning slot 212 and the stopping block 217. Thus, the stopping block 217 does not provide an effective function. PA1 (b) In the conventional fixing seat 20, an engaging block 218 is provided to one end of the two lateral walls 21. Thus, only one end of the engagement can be used and the stability of the fixing seat is limited. PA1 (c) The top section of the lateral walls 21 of the fixing seat 20 is exerted by force. The reinforcement structure at the bottom of the lateral walls 21 used to support the pressure of the control element 30 and the control shaft 40 is not sufficient. Thus, the fixing seat 20 may be deformed. PA1 (d) The pulling of the base slat 80 and blind slats 70 by the suspension cord 60 is not smooth. Due to the direct pulling of the structure, the user requires a stronger force to offset the total weight of the slats 70 and the base slat 80. Thus, it is not convenient for the weaker user or children to operate the venetian blinds.